1. Field of the Invention
The present invention relates to thin-film magnetic heads used for magneto-optical disk units, hard magnetic disk drives, etc. and to a method of making the same.
2. Description of the Related Art
A conventional thin-film magnetic head will be described with reference to FIGS. 15 to 18.
FIG. 15 is a plan view of a side 2a of a slider 2 (see FIG. 16) provided with a head element 1 of a thin-film magnetic head. The slider 2 is composed of a ceramic such as Al2O3xe2x80x94TiC, and an underlying layer 2b composed of Al2O3 or the like is formed at the side 2a. The side 2a of the slider 2 includes a head region A1, terminal regions A3 for supplying power to the head element 1, and a leader-section region A2 for connecting the head element 1 to a first terminal 19a and a second terminal 19b. The head element 1 lies in the head region A1, and includes a read section h11for reading data from hard magnetic disks and a write section h2 for writing data.
FIG. 16 is a perspective view of the head element 1 and FIG. 17 is a portion of a sectional view taken along the line 17xe2x80x9417 of FIG. 15. As shown in FIGS. 16 and 17, the read section h1 includes a lower shielding layer 3 composed of a magnetic material such as a permalloy formed on the underlying layer 2b at the side 2a, a lower gap layer 4 composed of an insulating material such as Al2O3 formed on the lower shielding layer 3, a magnetoresistive element layer 5 formed on the end of the lower gap layer 4 facing a medium, a hard bias layer 6 connected to both sides of the magnetoresistive element layer 5, an electrode layer 7 composed of a good conductor which is connected to the hard bias layer 6 and extends to the surface of the lower gap layer 4, an upper gap layer 8 composed of an insulating material such as alumina formed above the lower shielding layer 3 for covering the magnetoresistive element layer 5, the hard bias layer 6, and the electrode layer 7, and an upper shielding layer which also acts as a lower core 9 composed of a magnetic material formed on the upper gap layer 8.
The write section h2 of the head element 1 includes the lower core 9 composed of a magnetic material such as a permalloy, a gap layer 11 composed of an insulating material such as alumina formed on the lower core 9, a first insulating layer 12 composed of an insulating organic material formed on the gap layer 11, a window 10 provided so that a portion of the lower core 9 is exposed through the first insulating layer 12, a coil 13 composed of a good conductor such as copper spirally wound around the window 10 in the first insulating layer 12, an end 13a of the coil 13 extending from the surface of the first insulating layer 12 to the surface of the side 2a of the slider 2, a nickel film 14 formed on the coil 13 and the end 13a for inhibiting oxidation, a second insulating layer 15 composed of an insulating organic material for covering the surface of the coil 13 coated with the nickel film 14, an opening (not shown in the drawing) provided so that the other end (not shown in the drawing) of the coil 13 is exposed through the second insulating layer 15, and an upper core 16 composed of a magnetic material such as a FeNi alloy (permalloy) formed on the surface of the second insulating layer 15 and connected to the lower core 9 through the window 10.
The upper core 16 is opposed to the lower core 9 with the gap layer 11 therebetween at the end of the head element 1 facing the medium, and the width of the tip of the upper core 16 is narrowed at this end.
FIG. 18 is a portion of a sectional view taken along the line 18xe2x80x9418 of FIG. 15. As shown in FIGS. 15 and 18, a first leader section 18a, which extends from the end 13a of the coil 13 to the terminal region A3, is formed in the leader-section region A2. The first leader section 18a, which is composed of the same material as that of the upper core 16, overlaps the end 13a of the coil 13 in the head region A1 and extends to the terminal region A3. The end of the first leader section 18a constitutes a first terminal 19a formed in the terminal region A3.
A second leader section 18b, which extends from the other end (not shown in the drawing) of the coil 13 to the terminal region A3, is formed in the leader-section region A2. The second leader section 18b, which is composed of the same magnetic material as that of the upper core 16, is connected to the other end of the coil 13 and extends to the terminal region A3. The end of the second leader section 18b constitutes a second terminal 19b formed in the terminal region A3.
The slider 2 is mounted on a flexure (not shown in the drawing) which is flexible so that the side 2a is perpendicular to the surface of the medium, such as a hard magnetic disk.
When the hard magnetic disk drive is operated, a current is applied to the coil 13 from the first and second terminals 19a and 19b through the first and second leader sections 18a and 18b, respectively. Magnetic fields, which are induced by the current flowing through the coil 13, in the upper core 16 and the lower core 9, form a magnetic path at a gap G. Data is written on to the medium by a magnetic field of the magnetic path passing through the medium.
Next, a method of fabricating the coil 13, the upper core 16, and the first and second leader sections 18a and 18b will be described with reference to FIGS. 19 to 27.
The read section h1 is formed on the underlying layer 2b composed of Al2O3 or the like at the side 2a of the slider 2, and the gap layer 11 and the first insulating layer 12 are patterned on the lower core 9, which also acts as an upper shielding layer of the read section h1, so that a portion of the lower core 9 is exposed at the window 10.
In such a state, first, as shown in FIG. 19, an underlying layer 22 composed of a thin metal film for preparing plating is formed by sputtering over the first insulating layer 12 and the underlying layer 2b. An outline of the coil 13 is formed by a resist frame 23 on the surface of the underlying layer 22.
In the coil-forming step, a copper plating film 24 is formed on the underlying layer 22 provided with the resist frame 23, and a nickel plating film 25 for inhibiting oxidation of the copper is deposited thereon.
After the resist frame 23 is removed by a resist stripper, in a first ion milling step shown in FIG. 20, the surface of the nickel plating film 25 which covers the copper plating film 24 and the surface of a removable underlying layer 22a, which has been exposed by the resist-stripping, are irradiated with Ar ions, and the removable underlying layer 22a is eliminated so that insulating spaces are formed between turns of the coil 13.
Next, unnecessary copper plating film 24 and nickel plating film 25 are removed by wet etching while the surface of the nickel plating film 25 constituting the coil 13 is protected with a resist, and then the resist is stripped.
In a second ion milling step shown in FIG. 21, the surface of the nickel plating film 14 which covers the coil 13 and the surface of an unnecessary underlying layer 22b exposed by the wet etching are irradiated with Ar ions, and the exposed unnecessary underlying layer 22b is eliminated.
When the coil 13 is completed, as shown in FIG. 22, the end 13a of the coil 13 is formed in the head region A1.
In a subsequent step for forming the second insulating layer, an organic film is applied on the side 2a of the slider 2 in which the coil 13 has been formed, and the second insulating layer 15 is formed above the first insulating layer 12 so as to cover the coil 13. At this stage, the second insulating layer 15 is patterned so that the end 13a of the coil 13 and the other end are exposed.
Next, as shown in FIG. 23, an underlying layer 27 which is a thin metal film for plating is formed by sputtering on the second insulating layer 15, the end 13a of the coil 13, and the underlying layer 2b composed of Al2O3 or the like at the side 2a. 
An outline of the upper core 16, an integrated outline of the first leader section 18a which overlaps the end 13a of the coil 13 and the first terminal 19a, and, although not shown in FIG. 23, an integrated outline of a joint for connecting to other end of the coil 13, the second leader section 18b, and the second terminal 19b, are formed on the underlying layer 27 using a resist frame 28.
Next, in a step for integrally forming the upper core and the leader section, a FeNi alloy (permalloy) plating film 29 is formed on the underlying layer 27 provided with the resist frame 28.
The resist frame 28 is then removed by a resist stripper, and in a third ion milling step shown in FIG. 24, the surface of an exposed underlying layer 27a exposed by the removal of the resist frame 28 and the surface of the permalloy plating film 29 are irradiated with Ar ions, and the exposed underlying layer 27a is eliminated.
As shown in FIG. 25, the surface of the permalloy plating film 29 in the portions for forming leader sections, terminals, and a joint 20 is protected by a protective resist 30.
Next, in an upper core wet etching step, the unnecessary permalloy plating film 29 is removed by wet etching, and thus, the upper core 16, the leader sections 18a and 18b, the terminals 19a and 19b, and the joint 20 are formed.
After the protective resist 30 is stripped, in a fourth ion milling step shown in FIG. 26, the surfaces of the upper core 16, the leader sections 18a and 18b, and the terminals 19a and 19b, and the surface of an unnecessary underlying layer 27b exposed by the second wet etching are irradiated with Ar ions, and the unnecessary underlying layer 27b is eliminated.
FIG. 27 shows a structure in which the coil 13, the upper core 16, the first and second leader sections 18a and 18b, and the first and second terminals 19a and 19b are completed.
In the conventional thin-film magnetic head, since the first leader section 18a extending from the end 13a of the coil 13 to the terminal region A3 and the upper core 16 are composed of the same magnetic material, the first leader section 18a has a high wiring resistance, thus increasing power consumption.
Since the second leader section 18b extending from the other end of the coil 13 to the terminal region A3 and the upper core 16 are also composed of the same magnetic material, the second leader section 18b has a high wiring resistance, thus increasing power consumption.
In view of the conductivity of the leader sections 18a and 18b, a permalloy composed of a FeNi alloy having a low resistivity is used as the material for the upper core 16, which is the same material as that for the first and second leader sections 18a and 18b. Thereby, an eddy current induced by an alternating current of the coil 13 easily flows through the upper core 16, and a current is consumed by the eddy current, thus increasing power consumption.
It is an object of the present invention to provide a thin-film magnetic head in which wiring resistance is decreased, resulting in low power consumption. It is another object of the present invention to provide a thin-film magnetic head in which the eddy current loss is reduced, resulting in low power consumption. It is another object of the present invention to provide a method of producing such thin-film magnetic heads.
In one aspect, a thin-film magnetic head in accordance with the present invention includes a magnetic lower core provided on a slider, a first insulating layer formed on the lower core, a spiral coil composed of a good conductor formed on the first insulating layer, a first leader section composed of a good conductor formed on the slider, the first leader section being connected to an end of the coil and extending to a terminal region provided on the slider, a second insulating layer formed on the first insulating layer so as to cover the coil, and a magnetic upper core formed on the second insulating layer, the upper core being in contact with the lower core at the center of the coil. A first protective magnetic film is formed on the surface of the first leader section.
The thin-film magnetic head may further include a second leader section composed of a good conductor extending from the vicinity of the coil to the terminal region provided on the slider, and a second protective magnetic film for covering the surface of the second leader section, the second protective magnetic film being connected to the other end of the coil exposed through the second insulating layer.
Preferably, the upper core and the magnetic film formed on the surface of the leader section are composed of an alloy containing at least one element selected from the group consisting of Fe, Co, and Ni.
In another aspect, a thin-film magnetic head in accordance with the present invention includes a magnetic lower core provided on a slider, a first insulating layer formed on the lower core, a spiral coil formed on the first insulating layer, a leader section composed of a good conductor formed on the slider, the leader section being adjacent to the coil and extending to a terminal region provided on the slider, a second insulating layer formed on the first insulating layer so as to cover the coil, and a magnetic upper core formed on the second insulating layer, the upper core being in contact with the lower core at the center of the coil. A protective magnetic film, which is connected to the coil, is formed to cover the surface of the leader section.
Preferably, the upper core and the protective magnetic film formed on the surface of the leader section are composed of an alloy containing at least one element selected from the group consisting of Fe, Co, and Ni.
In another aspect, a method of producing a thin-film magnetic head in accordance with the present invention includes a first-insulating-layer-forming step for forming a first insulating layer on a magnetic lower core; a coil-and-leader-section-forming step for simultaneously forming a coil and a leader section connected to the coil and extending to a terminal region provided on the slider and/or a leader section extending from the vicinity of the coil to the terminal region provided on the slider using the same good conductor; a second-insulating-layer-forming step for forming a second insulating layer on the slider so as to cover the coil; and an upper-core-and-protective-film-forming step for simultaneously forming a protective magnetic film on the surface of the leader section and an upper core on the second insulating layer using the same magnetic material.
In the method of producing the thin-film magnetic head, preferably, the upper core and the protective magnetic film formed on the surface of the leader section are composed of an alloy containing at least one element selected from the group consisting of Fe, Co, and Ni.